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  <section id="findjni">
<span id="module:FindJNI"></span><h1>FindJNI<a class="headerlink" href="#findjni" title="Link to this heading">¶</a></h1>
<p>Finds the Java Native Interface (JNI) include directories and libraries.</p>
<p>JNI enables Java code running in a Java Virtual Machine (JVM) or Dalvik Virtual
Machine (DVM) on Android to call and be called by native applications and
libraries written in other languages such as C and C++.</p>
<p>This module finds if Java is installed and determines where the
include files and libraries are.  It also determines what the name of
the library is.</p>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24: </span>Imported targets, components, and Android NDK support.</p>
<p>When using Android NDK, the corresponding package version is reported and a
specific release can be requested. At Android API level 31 and above, the
additional <code class="docutils literal notranslate"><span class="pre">NativeHelper</span></code> component can be requested. <code class="docutils literal notranslate"><span class="pre">NativeHelper</span></code> is
also exposed as an implicit dependency of the <code class="docutils literal notranslate"><span class="pre">JVM</span></code> component (only if this
does not cause a conflict) which provides a uniform access to JVM functions.</p>
</div>
<section id="components">
<h2>Components<a class="headerlink" href="#components" title="Link to this heading">¶</a></h2>
<p>This module supports optional components, which can be specified with the
<span class="target" id="index-0-command:find_package"></span><a class="reference internal" href="../command/find_package.html#command:find_package" title="find_package"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">find_package()</span></code></a> command:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">find_package(</span><span class="no">JNI</span><span class="w"> </span><span class="p">[</span><span class="no">COMPONENTS</span><span class="w"> </span><span class="nv">&lt;components&gt;...</span><span class="p">]</span><span class="nf">)</span>
</pre></div>
</div>
<p>Supported components include:</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">AWT</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Finds the Java Abstract Window Toolkit (AWT).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JVM</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Finds the Java Virtual Machine (JVM).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">NativeHelper</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Finds the NativeHelper library on Android (<code class="docutils literal notranslate"><span class="pre">libnativehelper.so</span></code>), which
exposes JVM functions such as <code class="docutils literal notranslate"><span class="pre">JNI_CreateJavaVM()</span></code>.</p>
</dd>
</dl>
<p>If no components are specified, the module defaults are:</p>
<ul class="simple">
<li><p>When targeting Android with API level 31 and above: module looks for the
<code class="docutils literal notranslate"><span class="pre">NativeHelper</span></code> component.  For other Android API levels, components are by
default not set.</p></li>
<li><p>When targeting other systems: module looks for <code class="docutils literal notranslate"><span class="pre">AWT</span></code> and <code class="docutils literal notranslate"><span class="pre">JVM</span></code> components.</p></li>
</ul>
</section>
<section id="imported-targets">
<h2>Imported Targets<a class="headerlink" href="#imported-targets" title="Link to this heading">¶</a></h2>
<p>This module provides the following <a class="reference internal" href="../manual/cmake-buildsystem.7.html#imported-targets"><span class="std std-ref">Imported Targets</span></a>:</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">JNI::JNI</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Main target encapsulating all JNI usage requirements, available if <code class="docutils literal notranslate"><span class="pre">jni.h</span></code>
is found.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI::AWT</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Target encapsulating the Java AWT Native Interface (JAWT) library usage
requirements, available if the <code class="docutils literal notranslate"><span class="pre">AWT</span></code> component is found.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI::JVM</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Target encapsulating the Java Virtual Machine (JVM) library usage
requirements, available if component <code class="docutils literal notranslate"><span class="pre">JVM</span></code> is found.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI::NativeHelper</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Target encapsulating the NativeHelper library usage requirements, available
when targeting Android API level 31 and above, and the library is found.</p>
</dd>
</dl>
</section>
<section id="result-variables">
<h2>Result Variables<a class="headerlink" href="#result-variables" title="Link to this heading">¶</a></h2>
<p>This module defines the following variables:</p>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_FOUND</span></code></dt><dd><p>Boolean indicating whether the JNI is found.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_&lt;component&gt;_FOUND</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Boolean indicating whether the <code class="docutils literal notranslate"><span class="pre">&lt;component&gt;</span></code> is found.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_VERSION</span></code></dt><dd><p>Full Android NDK package version (including suffixes such as <code class="docutils literal notranslate"><span class="pre">-beta3</span></code> and
<code class="docutils literal notranslate"><span class="pre">-rc1</span></code>) or undefined otherwise.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_VERSION_MAJOR</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Android NDK major version or undefined otherwise.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_VERSION_MINOR</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Android NDK minor version or undefined otherwise.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_VERSION_PATCH</span></code></dt><dd><div class="versionadded">
<p><span class="versionmodified added">Added in version 3.24.</span></p>
</div>
<p>Android NDK patch version or undefined otherwise.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_INCLUDE_DIRS</span></code></dt><dd><p>The include directories needed to use the JNI.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JNI_LIBRARIES</span></code></dt><dd><p>The libraries (JAWT and JVM) needed to link against to use JNI.</p>
</dd>
</dl>
</section>
<section id="cache-variables">
<h2>Cache Variables<a class="headerlink" href="#cache-variables" title="Link to this heading">¶</a></h2>
<p>The following cache variables are also available to set or use:</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">JAVA_INCLUDE_PATH</span></code></dt><dd><p>The directory containing the <code class="docutils literal notranslate"><span class="pre">jni.h</span></code> header.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JAVA_INCLUDE_PATH2</span></code></dt><dd><p>The directory containing machine-dependent headers <code class="docutils literal notranslate"><span class="pre">jni_md.h</span></code> and
<code class="docutils literal notranslate"><span class="pre">jniport.h</span></code>.  This variable is defined only if <code class="docutils literal notranslate"><span class="pre">jni.h</span></code> depends on one of
these headers.  In contrast, Android NDK <code class="docutils literal notranslate"><span class="pre">jni.h</span></code> can be typically used
standalone.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JAVA_AWT_INCLUDE_PATH</span></code></dt><dd><p>The directory containing the <code class="docutils literal notranslate"><span class="pre">jawt.h</span></code> header.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JAVA_AWT_LIBRARY</span></code></dt><dd><p>The path to the Java AWT Native Interface (JAWT) library.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">JAVA_JVM_LIBRARY</span></code></dt><dd><p>The path to the Java Virtual Machine (JVM) library.</p>
</dd>
</dl>
</section>
<section id="hints">
<h2>Hints<a class="headerlink" href="#hints" title="Link to this heading">¶</a></h2>
<p>This module accepts the following variables:</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">JAVA_HOME</span></code></dt><dd><p>The caller can set this variable to specify the installation directory of Java
explicitly.</p>
</dd>
</dl>
</section>
<section id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading">¶</a></h2>
<p>Finding JNI and linking it to a project target:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">find_package(</span><span class="no">JNI</span><span class="nf">)</span>
<span class="nf">target_link_libraries(</span><span class="nb">project_target</span><span class="w"> </span><span class="no">PRIVATE</span><span class="w"> </span><span class="no">JNI</span><span class="o">::</span><span class="no">JNI</span><span class="nf">)</span>
</pre></div>
</div>
<p>Finding JNI with AWT component specified and linking them to a project target:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">find_package(</span><span class="no">JNI</span><span class="w"> </span><span class="no">COMPONENTS</span><span class="w"> </span><span class="no">AWT</span><span class="nf">)</span>
<span class="nf">target_link_libraries(</span><span class="nb">project_target</span><span class="w"> </span><span class="no">PRIVATE</span><span class="w"> </span><span class="no">JNI</span><span class="o">::</span><span class="no">JNI</span><span class="w"> </span><span class="no">JNI</span><span class="o">::</span><span class="no">AWT</span><span class="nf">)</span>
</pre></div>
</div>
<p>A more common way to use Java and JNI in CMake is to use a dedicated
<span class="target" id="index-0-module:UseJava"></span><a class="reference internal" href="UseJava.html#module:UseJava" title="UseJava"><code class="xref cmake cmake-module docutils literal notranslate"><span class="pre">UseJava</span></code></a> module:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">find_package(</span><span class="nb">Java</span><span class="nf">)</span>
<span class="nf">find_package(</span><span class="no">JNI</span><span class="nf">)</span>
<span class="nf">include(</span><span class="nb">UseJava</span><span class="nf">)</span>
</pre></div>
</div>
</section>
<section id="see-also">
<h2>See Also<a class="headerlink" href="#see-also" title="Link to this heading">¶</a></h2>
<ul class="simple">
<li><p>The <span class="target" id="index-0-module:FindJava"></span><a class="reference internal" href="FindJava.html#module:FindJava" title="FindJava"><code class="xref cmake cmake-module docutils literal notranslate"><span class="pre">FindJava</span></code></a> module to find Java runtime tools and development
components.</p></li>
<li><p>The <span class="target" id="index-1-module:UseJava"></span><a class="reference internal" href="UseJava.html#module:UseJava" title="UseJava"><code class="xref cmake cmake-module docutils literal notranslate"><span class="pre">UseJava</span></code></a> module to use Java in CMake.</p></li>
</ul>
</section>
</section>


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    <h3>Table of Contents</h3>
    <ul>
<li><a class="reference internal" href="#">FindJNI</a><ul>
<li><a class="reference internal" href="#components">Components</a></li>
<li><a class="reference internal" href="#imported-targets">Imported Targets</a></li>
<li><a class="reference internal" href="#result-variables">Result Variables</a></li>
<li><a class="reference internal" href="#cache-variables">Cache Variables</a></li>
<li><a class="reference internal" href="#hints">Hints</a></li>
<li><a class="reference internal" href="#examples">Examples</a></li>
<li><a class="reference internal" href="#see-also">See Also</a></li>
</ul>
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